<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
</head>
<body>
	
</body>
<script>
	console.log(Number(null))
	console.log(Number(""))
	console.log(Number(false))


	console.log(Number(undefined))
	console.log(Number({}))
	console.log(Number(NaN))
	console.log(Number("a123a"))
	console.log(Number("123a"))


    console.log(parseInt(null))
    console.log(parseInt(""))
    console.log(parseInt(false))
    console.log(parseInt(undefined))
    console.log(parseInt({}))
    console.log(parseInt("a123a"))

    console.log(parseInt("123a"))
	console.log(1+{})
    console.log(1+[]+1)
	console.log(1+function(){
		console.log(11)
	})
    console.log(1+null)
    console.log(1+"1")
    console.log(1+true)
    console.log(1+false)
    console.log(1+undefined)

 var test= new String("111 111");
 console.log(test)

 var test1= new String("hello");
 console.log(typeof test1.valueOf())
var str='hello world'
let num=str.indexOf('w')
let num2='this is my mom'
console.log(num2.replace(/\s+is\s+/g,'ok'))

 console.log(str.slice(num))

</script>
</html>